JPH0756384A - Two-component magnetic developer toner excellent in anti-spent property - Google Patents

Abstract

PURPOSE:To provide such a two-component magnetic developer toner containing no charge controlling agent (CCA-less) that the toner is excellent in spent resistance, the life of the toner and the carrier can be extended, the toner contains no transferrable charge controlling agent, and the apparent development sentivity can be increased without splashing of the toner during development, and further, to provide a CCA-less two-component magnetic developer with which transfer from the surface of a photosensitive body to a paper sheet can be efficiently done although no transferrable charge controlling agent is incorporated. CONSTITUTION:A copolymer resin or resin compsn. having anionic polar groups is used as a fixing resin medium. The toner contains a 0.1-5 pts.wt. of magnetic powder to 100 pts.wt. of the resin medium. This toner is prepared in such a manner that an extract of the toner with methanol shows substantially no absorptivity at absorption peaks of 400-700nm and 280 to 350nm. Further, a fluidity improving agent to be externally added to the toner contains spacer particles having 0.05-1mum particle size.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a toner for a two-component magnetic developer having excellent spent resistance, and more specifically, it does not contain a transferable charge control agent in the toner particles.
In addition, the present invention relates to a toner that does not scatter toner during development, is efficiently transferred, can form a high density image, and has a long life of the toner and carrier.

[0002]

2. Description of the Related Art A so-called two-component magnetic developer is widely used as a developer for developing an electrostatic charge image formed on an electrophotographic photosensitive member.

This two-component magnetic developer is composed of a composition of a magnetic carrier composed of iron powder, ferrite particles and the like, and an electroscopic toner composed of a colored resin composition.
During development, by mixing a magnetic carrier and toner, the toner particles are charged to a constant polarity, the mixture is conveyed to the photoconductor in the form of a magnetic brush, and the surface of the photoconductor is rubbed with the magnetic brush. The charged toner is adsorbed and held on the charge image on the surface of the photoconductor to form a visible image.

In order to control the polarity of toner particles by triboelectric charging to be constant, it is common to include a charge control agent in the toner particles. For negatively chargeable toner, metal-containing complex salt dye or oxycarboxylic acid is used. A negative charge control agent such as a metal complex of an acid is used (for example, Japanese Patent Laid-Open No. 3-67268), and for a positively chargeable toner, a positive chargeability control such as an oil-soluble dye such as nigrosine or an amine-based control agent is used. Agent (for example, JP-A-56
No. 106249) is used.

It has been known for a long time to use a magnetic toner as a toner for a two-component magnetic developer, for example, the above-mentioned JP-A-56-106249 and JP-A-59-1.
Japanese Patent Laid-Open No. 62563 describes use of a magnetic powder internally-added toner in which magnetic powder is contained in the toner, while Japanese Patent Application Laid-Open No. 3-67268 discloses adding and mixing silica powder and magnetic powder to a toner base. The magnetic powder externally added toner is described.

[0006]

The two-component magnetic developer is
It is known that in the initial stage of using the magnetic carrier and the toner mixed, even if the charging performance is satisfactory, the charging performance deteriorates due to the generation of so-called spent (toner) and the life thereof becomes short. There is.

The spent (toner) is a phenomenon in which the toner component adheres to and deposits on the surface of the magnetic carrier in the form of a film, and the surface of the magnetic carrier becomes closer to that of the toner. However, the predetermined charging performance cannot be obtained. Thus, when the spent occurs, the magnetic carrier must be discarded and replaced with a new magnetic carrier.

Therefore, an object of the present invention is to provide a two-component magnetic developer which is excellent in spent resistance and has a long life of toner and carrier.

Another object of the present invention is to contain no transferable charge control agent in the toner particles and to contain CCA (charge control agent) capable of increasing apparent development sensitivity without scattering of toner during development. To provide a toner for a two-component magnetic developer which does not include (CCA).

Still another object of the present invention is to provide a CCA-less two-component magnetic developer which allows efficient transfer from the surface of the photoconductor to paper, even though it does not contain a transferable charge control agent. There is.

[0011]

According to the present invention, in a negatively charged toner for a two-component magnetic developer, a fixing resin medium is a copolymer resin or a resin composition having an anionic polar group, An absorption liquid having an absorption peak at wavelengths of 400 to 700 nm and 280 to 350 nm of the extract containing 0.1 to 5 parts by weight of magnetic powder per 100 parts by weight of the medium and extracting the toner with methanol is substantially zero. And a toner for a two-component magnetic developer excellent in spent resistance.

According to the present invention, the above toner, in particular, toner particles having a volume-based particle size of 5 to 15 μm contains spacer particles having a volume-based particle size of 0.05 to 1.0 μm on the surface thereof to improve fluidity of fine powder. A toner for a two-component magnetic developer excellent in spent resistance and transfer efficiency, which is characterized in that an agent is adhered.

[0013]

The present inventors have found the following interesting facts in the course of repeated research to prevent toner spent generation.

FIG. 1 of the accompanying drawings shows that of a conventional two-component magnetic developer toner used for developing a positively charged image, a toner containing a chromium complex salt dye (2: 1 type) as a charge control agent is methanol. Wavelength of extracted liquid 400 to 700n
2 is an absorbance curve at m, and FIG. 2 is an absorbance curve at a wavelength of 280 to 350 nm of a methanol extract of a toner using a salicylic acid metal complex as a charge control agent.

According to these results, all the extraction liquids showed characteristic absorption peaks due to the charge control agent, which means that the surface of the toner particles contained the charge control agent in a considerably high concentration. ing. This is in good agreement with the idea that the charge control agent migrates to the surface of the toner particles even if it is internally added to the toner, and this migration controls the charge due to triboelectrification.

On the other hand, in FIG. 3, the toner used in the measurement of FIG. 1 was used as a two-component magnetic developer, and a carrier in which charge failure occurred due to spent was similarly extracted with methanol, and the wavelength of this extract was measured. 400 to 700 nm
Is the measured absorbance curve.

According to the measurement results, the charge control agent is deposited and deposited at a high concentration on the carrier surface, and the charging failure due to the spent is not the mere filming of the carrier surface due to the toner resin, which has been considered in the past. The surprising fact of migration of the control agent to the carrier surface was revealed.

This fact becomes more apparent with reference to FIGS. 4 and 5. FIGS. 4 and 5 show the relationship between the mixing time and the amount of spent when mixing a mixture of a toner containing a charge control agent and a magnetic carrier and a mixture of a toner containing no charge control agent and a magnetic carrier. The relationship between the time and the charge amount is plotted. From these results, it becomes clear that the toner containing the charge control agent has a larger amount of spent than the toner not containing the charge control agent, resulting in a large decrease in the charge amount.

Furthermore, FIG. 6 shows the relationship between the amount of spent spent carrier and the charge control agent in the spent toner, and the dotted line in FIG. 6 indicates the predicted value calculated from the toner prescription. It is a plot. According to this result, it becomes clear that the charge control agent is selectively transferred to and adheres to the carrier surface in the early stage of spent generation. 5 and 6 show the results in the closed system without toner replenishment, and it can be expected that the difference due to the presence or absence of the charge control agent will be further widened when the toner is replaced in the copying machine.

Furthermore, FIG. 7 shows the relationship between the mixing time and the amount of spent when the individual components in the toner are mixed with the magnetic carrier. According to this result,
It has been clarified that the charge control agent is a component that easily migrates to the carrier surface among the various components in the toner and tends to generate spent.

From the above, the charging failure due to the spent generation in the conventional two-component magnetic developer is as shown in the explanatory view of FIG. 8, in which the carrier is positively charged and the toner is negatively charged at the beginning of mixed use. It can be explained that the other thing is that as the spent formed by the selective transfer of the charge control agent to the surface of the carrier is formed, the spent layer is negatively charged and the opposite polarity toner positively charged is formed.

In the present invention, in order to prevent the transfer of the charge control agent to the surface of the magnetic carrier, the internal addition or blending of the transfer charge control agent to the toner particles is stopped. Along with this, the toner of the present invention, as shown in the absorbance curve of FIG.
Even when extracted with methanol, this methanol extract has no absorption peak at wavelengths of 400 to 700 nm, or the absorption peak is substantially zero even if it exists. Further, as shown in the absorbance curve in FIG. 9, even when the absorbance of the above extract was measured at a wavelength of 280 to 350 nm, there was no absorption peak and the absorbance was substantially zero. Thus, the first feature of the present invention is that the transfer of the charge control agent to the surface of the carrier is suppressed and the spent resistance is improved.

By the way, as shown in FIG. 5, the toner containing no charge control agent has an insufficient charge amount as compared with the toner containing the charge control agent. In the present invention,
In order to prevent this, a copolymer resin or resin composition having an anionic polar group is used as the fixing resin medium. By using this resin or resin composition, the minimum charge controllability of triboelectric charging can be obtained during development.

The anionic polar group gives the toner charge controllability, but since it is bonded to the resin skeleton, it does not migrate to the surface of the toner particle, but on the other hand, the toner particle and the carrier in the magnetic brush at the time of development. Coupling with and due to Coulomb force weakens, and the higher the speed of copying, the more
Toner scattering becomes remarkable, which causes a drawback that the toner in the copying machine is contaminated and the fog density of the copy is increased.

In the present invention, in order to prevent this, a specific amount of magnetic powder is contained in the toner, and in addition to the Coulomb force of the toner-carrier, the magnetic attraction of the toner-carrier prevents toner scattering. To do so.

In the present invention, it is one of the remarkable advantages of the present invention that the apparent sensitivity during development can be increased while preventing toner scattering. That is, the smaller the amount of charge per toner particle, the greater the number of toner particles attached to the electrostatic latent image having a constant charge amount, so that the apparent developing sensitivity increases.

In the present invention, the magnetic powder is added in a small amount such as 0.1 to 5 parts by weight, particularly 0.5 to 3.0 parts by weight, per 100 parts by weight of the resin medium, while preventing toner scattering. It is a remarkable advantage that a high density image can be formed.
That is, in the conventional magnetic toner used in the two-component magnetic developer, the magnetic powder is used in an amount of more than 10 parts by weight per 100 parts by weight of the resin medium, but the amount used in the present invention is considerably smaller than this. is there. If the amount of magnetic powder used is less than 0.1 parts by weight, toner scattering tends to occur, while if it is more than 5 parts by weight, the development density decreases.

The toner of the present invention is generally 5 to 15 μm.
However, it is desirable to externally add a fine powder fluidity improving agent containing spacer particles having a particle diameter of 0.05 to 1.0 μm to the surface of the toner particles.

Generally, in order to improve the powdery fluidity of the toner, a fluidity improver such as fine particle silica is externally attached and used. In the present invention, the fluidity improver is added to the fluidity improver. By interposing spacer particles having a particle size of 0.05 to 1.0 μm, the bond between the toner image and the latent image on the surface of the photoconductor is weakened so that the toner image can be easily peeled off. It succeeded in improving the transfer efficiency in the transfer process.

[0030]

Preferred Embodiment of the Invention

[Resin Medium] The fixing resin medium used in the present invention is a copolymer resin or resin composition having an anionic polar group. Examples of the anionic polar group include any polar group such as carboxylic acid, sulfonic acid, phosphonic acid and the like, and a carboxylic acid type group is particularly preferable. The copolymer resin having an anionic polar group is a resin having a monomer having an anionic polar group incorporated into the resin by random copolymerization, block copolymerization, graft copolymerization or the like. Suitable examples of comonomers are:

Examples of the carboxylic acid type include ethylenically unsaturated carboxylic acids, for example, lower alkyl half esters such as acrylic acid, methacrylic acid, crotonic acid, maleic acid, maleic anhydride, fumaric acid, maleic acid or fumaric acid. Etc.

Examples of the sulfonic acid type include styrene sulfonic acid and 2-acrylamido-2-methylpropane sulfonic acid.

Examples of the phosphonic acid type include 2-acid phosphoxypropyl methacrylate, 2-acid phosphoxyethyl methacrylate, 3-chloro-2-acid phosphoxypropyl methacrylate and the like.

These anionic polar group-containing monomer units are neutralized with alkali acids such as sodium and potassium, alkaline earth metals such as calcium and magnesium, and zinc even if they are free acids. May be.

The other monomer, which is the main component of the resin or resin composition, is the one in which the resulting polymer has the fixing property and the electric detection property required for the toner, and is a monomer having an ethylenically unsaturated bond. One or a combination of two or more bodies is used.

Suitable examples of such a monomer include acrylic monomers, monovinyl aromatic monomers, vinyl ester monomers, vinyl ether monomers, diolefin monomers and monoolefins. System monomers and the like.

Examples of acrylic monomers include those represented by the formula:

[Chemical 1] In the formula, R ₁ is a hydrogen atom or a lower alkyl group, R ₂ is a hydrogen atom, a hydrocarbon group having up to 12 carbon atoms, or a hydroxyalkyl group, an acrylic monomer, particularly methyl acrylate, ethyl acrylate, Butyl acrylate, 2-ethylhexyl acrylate, cyclohexyl acrylate, phenyl acrylate, methyl methacrylate, hexyl methacrylate, 2-ethylhexyl methacrylate, ethyl β-hydroxyacrylate, γ-hydroxypropyl acrylate, δ- Examples thereof include butyl hydroxyacrylate and β-hydroxyethyl methacrylate.

As the monovinyl aromatic monomer, for example,

[Chemical 2] In the formula, R ₃ is a hydrogen atom, a lower alkyl group or a halogen atom, R ₄ is a hydrogen atom, a lower alkyl group, a halogen atom, an alkoxy group, an amino group, a nitro group or the like, and Φ
Is a phenylene group, a monovinyl aromatic hydrocarbon,
Examples thereof include styrene, α-methylstyrene, vinyltoluene, α-chlorostyrene, o-, m-, p-chlorostyrene, p-ethylstyrene and the like, or a combination of two or more thereof.

Examples of the other monomer include the followings.

Embedded image In the formula, CH═CH—OOCR ₅ , R ₅ is a hydrogen atom or a lower alkyl group, and is a vinyl ester such as vinyl formate, vinyl acetate, vinyl propionate and the like.

[0040]

Embedded image CH = CH-O-R ₆ Formula, R ₆ is a monovalent hydrocarbon group having up to 12 carbon atoms, vinyl ethers such as vinyl methyl ether, vinyl ethyl ether, vinyl -n- butyl ether, vinyl Phenyl ether, vinyl cyclohexyl ether, etc.

[0041]

[Chemical 5] In the formula, each of R ₇ , R ₈ and R ₉ is a hydrogen atom, a lower alkyl group or a halogen atom, and diolefins, particularly butadiene, isoprene and chloroprene.

[0042]

[Chemical 6] In the formula, each of R ₁₀ and R ₁₁ is a hydrogen atom or a lower alkyl group, especially monoolefins such as ethylene, propylene, isobutylene, butene-1, pentene-1, 4-methylpentene-1.

The copolymer resin having an anionic polar group used in the present invention, in the case of a free acid, is represented by an acid value of 2 to 3
It is desirable to have a concentration of anionic polar groups of 0, especially 5 to 15. Even when a part or all of the anionic polar group of the copolymer resin is neutralized, it is preferable to have the concentration of the anionic polar group corresponding to the above acid value.

When the concentration of the anionic polar group in the copolymer resin is less than the above range, the chargeability of the toner tends to be unsatisfactory, while when it is more than the above range, the toner becomes humidity sensitive, which is not preferable.

A suitable copolymer resin contains an anionic polar group-containing monomer and one or more kinds of the acrylic monomer of "Chemical formula 1" as essential components, and, if desired, "Chemical formula 2". To a copolymer resin containing the monomer of "Chemical Formula 6" as an optional component.

In the present invention, the anionic polar group-containing copolymer resin can be used alone as described above, or a composition containing two or more anionic polar group-containing copolymer resins,
Alternatively, it can be used as a fixing resin medium in the form of a composition of an anionic polar group-containing copolymer resin and a copolymer resin having no anionic polar group.

When the fixing resin medium is composed of a resin composition, the concentration of the anionic polar group in the resin composition as a whole should be within the range described above for the copolymer resin.

[Magnetic Powder] As the magnetic material pigment, magnetic powders conventionally used in magnetic toners, for example, iron trioxide (Fe ₃ O ₄ ), iron sesquioxide (γ-Fe ₂ O ₃ ), and oxidation Iron zinc (ZnFe ₂ O ₄ ), yttrium iron oxide (Y ₃
Fe ₅ O ₁₂ ), iron cadmium oxide (CdFe ₂ O ₄ ),
Iron oxide gadolinium (Gd ₃ Fe ₅ O ₁₂ ), iron oxide copper (C
uFe ₂ O ₄ ), lead iron oxide (PbFe ₁₂ O ₁₉ ), iron nickel oxide (NiFe ₂ O ₄ ), iron neodymium oxide (Nd)
FeO ₃ ), barium iron oxide (BaFe ₁₂ O ₁₉ ), magnesium iron oxide (MgFe ₂ O ₄ ), manganese iron oxide (MnFe ₂ O ₄ ), lanthanum iron oxide (LaFeO)
₃ ), iron powder (Fe), cobalt powder (Co), nickel powder (Ni) and the like can be used.

A magnetic powder particularly suitable for the purpose of the present invention is finely particulate iron sesquioxide (magnetite). The preferred magnetite is octahedral and has a particle size of 0.05 to 1.0 μm.
belongs to. The magnetite particles may be surface-treated with a silane coupling agent, a titanium coupling agent, or the like.

[Toner Composition] The toner composition of the present invention contains the fixing resin medium and the magnetic powder as an essential component, but other compounding agents that are conventionally compounded in the toner may be compounded. it can. Examples are colorants and release agents.

Suitable examples of colorants (pigments) are as follows. Black pigments Carbon black, acetylene black, run black, aniline black. Yellow pigment Yellow lead, zinc yellow, cadmium yellow, yellow iron oxide, mineral fast yellow, nickel titanium yellow, navels yellow, naphthol yellow S, Hansa yellow G, Hansa yellow 10G, benzidine yellow G,
Benzidine Yellow GR, Quinoline Yellow Lake, Permanent Yellow NCG, Tartrazine Lake. Orange pigment Red lead yellow molybdenum, Molybden orange, Permanent orange GTR, Pyrazolone orange, Balkan orange, Induslen brilliant orange RK, Benzidine orange G, Induslen brilliant orange GK. Red pigment Bengal, cadmium red, red lead, mercury cadmium sulfide, permanent red 4R, resole red, pyrazolone red, watching red calcium salt, lake red D, brilliant carmine 6B, eosin lake, rhodamine lake B, alizarin lake, brilliant carmine 3B. Purple pigment Manganese purple, fast violet B, methyl violet lake. Blue pigment Navy blue, cobalt blue, alkali blue lake, Victoria blue lake, phthalocyanine blue, metal-free phthalocyanine blue, phthalocyanine blue partial chlorinated compound, fast sky blue, indanthrene blue B
C. Green pigment chrome green, chrome oxide, pigment green B,
Malachite Green Rake, Fanal Yellow Green G. White pigment Zinc white, titanium oxide, antimony white, zinc sulfide. Extender barite powder, barium carbonate, clay, silica, white carbon, talc, alumina white.

The above pigment is used in an amount of 2 to 20 parts by weight, particularly 5 to 15 parts by weight, per 100 parts by weight of the fixing resin medium.

As the releasing agent for heat fixing, various waxes and low molecular weight olefin resins are used. As the olefin resin, polypropylene, polyethylene, and a propylene-ethylene copolymer are used, and polypropylene is particularly preferable.

[Toner Manufacturing Method] The toner of the present invention can be manufactured by a known method such as a pulverizing and classifying method, a melt granulating method, a spray granulating method and a polymerization method, but the pulverizing and classifying method is generally used. is there. Each of these toner components is pre-mixed with a mixer such as a Henschel mixer, and then kneaded with a kneading device such as a twin-screw extruder, and the kneaded composition is cooled and then pulverized,
Classify to make toner. The particle diameter of the toner is preferably such that the median diameter measured by a Coulter counter is in the range of 5 to 15 μm, particularly 7 to 12 μm.

If necessary, a fluidity improving agent such as hydrophobic vapor grown silica may be externally attached to the surface of the toner particles to improve the fluidity of the toner. The amount of the fluidity improver is preferably externally added in an amount of 0.1 to 2.0% by weight based on the toner. According to a preferred embodiment of the present invention, at this time, the fluidity improving agent contains spacer particles having a particle diameter of 0.05 to 1.0 μm, which is larger than the fluidity improving agent, to improve transfer efficiency. Let

As the spacer particles, any organic or inorganic inert particles having the above-mentioned particle size can be used, but in general, the above-mentioned magnetic powder, in particular, fine particulate ferric tetroxide (magnetite) is used. ) Is preferably used. This is because the magnetic powder existing on the surface of the toner particles also effectively acts on the toner scattering. Spacer particles such as fine particles of ferric tetroxide (magnetite) are preferably externally added in an amount of 0.1 to 10% by weight based on the toner. When externally adding the fluidity-improving agent and the spacer particles to the toner, it is necessary to thoroughly mix the fluidity-improving agent and the spacer particles in advance under pulverizing conditions, and to add the mixture to the toner to sufficiently disintegrate it. Good.

[Use] The toner according to the present invention is mixed with a magnetic carrier and used as a two-component developer. The magnetic carrier is preferably a ferrite-based magnetic carrier, particularly a soft ferrite containing at least one metal component selected from the group consisting of Cu, Zn, Mg, Mn and Ni, and preferably two or more, for example. Sintered ferrite particles of copper-zinc-magnesium ferrite, in particular spherical particles, are used. The surface of the magnetic carrier may be uncoated, but in general, it is preferably coated with silicone resin, fluorine resin, epoxy resin, amino resin, urethane resin or the like. The saturation magnetization of the carrier is preferably in the range of 30 to 70 emu / g, particularly 40 to 60 emu / g. The particle size of the magnetic carrier is 20 to 1
It is preferably in the range of 40 μm, particularly 50 to 100 μm.

The mixing ratio of the magnetic carrier and the toner is preferably 98: 2 to 90:10 by weight, particularly 97: 3 to 94: 6 by weight.

In the electrostatographic copying method using the toner of the present invention, the electrostatic latent image can be formed by any method known per se, for example, by uniformly charging the photoconductive layer on the conductive substrate. After that, imagewise exposure can be performed to form an electrostatic latent image. Development of the electrostatic image is easily performed by bringing a magnetic brush of a two-component magnetic developer into contact with the substrate.
The toner image formed by development is transferred onto copy paper,
Fixing is performed by bringing this toner image into contact with a heating roll.

[0060]

The present invention will be further described in the following examples. Example 1 (Toner Composition) (Parts by Weight) Fixing Resin 100 Styrene Acrylic Copolymer Having Carboxyl Group Colorant Carbon Black 7 Magnetic Powder Magnetite 2 The above composition was melt-kneaded by a twin-screw extruder and then this kneading Objects are crushed with a jet mill and classified with an air classifier,
Toner particles having an average particle diameter of 10.0 μm were obtained. The spacer particles have an average particle diameter of 0.015 μm.
The hydrophobic silica fine particles of m were added at a ratio of 0.3 parts by weight to 100 parts by weight of the toner particles and mixed for 2 minutes with a Henschel mixer to obtain the toner of the present invention. Example 2 A toner of the present invention was obtained in the same manner as in Example 1 except that acrylic resin particles having an average particle diameter of 0.15 μm were externally added as spacer particles. Example 3 A toner of the present invention was obtained in the same manner as in Example 1 except that magnetite particles having an average particle size of 0.4 μm were externally added as spacer particles.

Comparative Example 1 A toner was prepared in the same manner as in Example 1 except that a styrene-acrylic copolymer having no carboxyl group in the resin was used as the fixing resin. Comparative Example 2 A toner was obtained in the same manner as in Example 1 except that magnetite was not internally added. Comparative Example 3 A toner was obtained in the same manner as in Example 1 except that the amount of magnetite internally added to the toner was changed to 10 parts by weight. Comparative Example 4 A toner was obtained in the same manner as in Example 1 except that an azo dye (trade name "S-34" manufactured by Orient Chemical Co., Ltd.) was added as a charge control agent. Comparative Example 5 As a charge control agent, a salicylic acid derivative (trade name "E-8
4 ”manufactured by Orient Chemical Co., Ltd.) was added to obtain a toner in the same manner as in Example 1.

[Evaluation of Toner] (1) Measurement of Absorbance 100 mg of toner is precisely weighed and put in a sample bottle, 50 ml of methanol is added thereto, and the mixture is stirred for 10 minutes by a ball mill and then left for 15 hours. 20 ml of the supernatant is taken and subjected to centrifugation to measure the absorbance. The spectrophotometer "U-3
210 ”manufactured by Hitachi, Ltd. was used. The evaluation results are shown in Table 1.

[0063]

[Table 1]

(2) Evaluation Test The toners obtained in each of the examples and comparative examples were mixed with a ferrite carrier having an average particle size of 100 μm and uniformly mixed to prepare a two-component developer having a toner concentration of 3.5%. did.
Next, an electronic copier manufactured by Mita Kogyo Co., Ltd. (trade name "DC-7
085 ") was used to make 100,000 copies.
The manuscript used for copying is a character manuscript and the area ratio of the black part is 8%.
As the originals sampled for every predetermined number of sheets, those having an area ratio of black portions including black solid portions of 15% were used. Each test method is as follows.

(A) Image Density (ID) For every predetermined number of copies, the density of black solid parts in up to 100,000 copied images can be measured using a reflection densitometer (model number "TC-6D" manufactured by Tokyo Denshoku Co., Ltd.). It was measured using.

(B) Fog Density (FD) The density of the non-image area was measured with a reflection densitometer (model number "TC-6D" manufactured by Tokyo Denshoku Co., Ltd.), and the base paper (paper density before copying) was measured.
Expressed as the difference between The evaluation results are shown in Table 2.

(C) Resolution Copying was performed using a specified chart original, and the copied image had a peak value of 0.8 or more in a microdensitometer,
The number of lines having a base value of 0.4 or more and a difference between the peak value and the base value of 0.6 or more was counted. The evaluation results are shown in Table 2.

(D) Transfer Efficiency The amount of toner in the toner hopper before the start of copying and the amount in the toner hopper after copying a predetermined number of sheets were measured, and the toner consumption amount was calculated from the difference. On the other hand, the amount of toner collected in the cleaning process is measured during copying of a predetermined number of sheets,
The amount of toner collected was obtained. From these values, the toner transfer efficiency was calculated for every 20,000 sheets by the following formula. Table 2 shows the evaluation results
Shown in.

(E) Toner scattering The toner scattering inside the copying machine at the end of copying 100,000 sheets was visually observed and evaluated according to the following criteria. The evaluation results are shown in Table 2. ○: No toner scattering ×: Toner scattering

[0070]

[Table 2]

(F) Spent Amount The developer sampled for every predetermined number is placed on a 400-mesh screen, and the toner and carrier are separated by sucking from below with a blower. 5g of carrier remaining on the sieve
Is placed in a beaker, and toluene is further added to the beaker to disperse the toner adhering to the carrier surface. Then, the toluene solution is dropped from under the beaker while the carrier is attracted by the magnet. After repeating this several times until the toluene becomes colorless, the toluene is dried in an oven and the weight is measured. The difference between the weight put in the beaker and the weight after drying is the amount of spent. Spent amount is 1g carrier
It is expressed in mg of the spent toner attached around. The evaluation results are shown in Table 3.

(G) Toner charge amount 200 mg of developer was used as a "blow-off powder charge amount measuring device".
(Manufactured by Toshiba Chemical Co., Ltd.) and measured by a conventional method, and expressed as the amount of charge per 1 g of toner. The evaluation results are shown in Table 3.

(H) Electric Resistance of Developer 200 mg of the developer is put into a measuring jig having a distance between the electrodes of 2 mm, and a magnet of 1500 gauss is approached from both sides thereof to form a developer bridge between the electrodes. 1000 V was applied between the electrodes, and the electric resistance was calculated from the current flowing between the electrodes. The evaluation results are shown in Table 3.

[0074]

[Table 3]

(3) Consideration of Evaluation Results In Examples 1 to 3, the image density, fog, resolution and transfer efficiency were very stable, and the toner scattering was good. On the other hand, in Comparative Example 1 in which the resin having no anion group was used, the charge amount significantly increased as the number of copies increased, and the image density and the transfer efficiency decreased. Similarly, in Comparative Example 2 containing no magnetic powder, a large increase in charge amount occurred, and the image density and transfer efficiency deteriorated. In addition, the toner scattering tended to increase at an accelerated rate as the number of copies increased. In Comparative Example 3 in which the amount of magnetic powder was large, no increase in the charge amount was observed, but the image density was at a low level from the start point. Also, the resolution has dropped significantly. This is because the spiked state of the developer is too strong or the electric resistance of the developer is extremely high. In Comparative Examples 4 and 5 in which the charge control agent was used, the toner charge amount decreased as copying proceeded, causing an increase in fog and a decrease in transfer efficiency. The cause of the decrease in the toner charge amount is that the amount of spent toner is very large.

[0076]

According to the present invention, in a two-component magnetic developer toner used for positively charged images, a copolymer resin or resin composition having an anionic polar group is used as a fixing resin medium, and Extraction liquid of toner extracted with methanol wavelengths 400 to 700 nm and 280 to 350 nm
By making the absorbance of the absorption peak at 0 substantially zero, the minimum necessary charge controllability of triboelectrification can be obtained, and migration of the charge control agent to the carrier surface and charging failure due to this spent can be eliminated. Therefore, the charging performance of the toner can be stabilized for a long period of time, and the life of the toner and the carrier can be extended.

Further, by containing 0.1 to 5 parts by weight of magnetic powder per 100 parts by weight of the resin medium, toner scattering is prevented by the Coulomb force of the toner-carrier and the magnetic attraction of the toner-carrier. Will be done. Further, in the present invention, the charge amount per toner particle is set to a relatively low level, the number of toner particles attached to the electrostatic latent image having a constant charge amount is increased, and the apparent developing sensitivity is increased. You can

Furthermore, in a preferred embodiment of the present invention,
The particle size of the fluidity improver externally added to the toner is 0.05 to 1
By interposing spacer particles of μm, the bond between the toner image and the latent image on the surface of the photoconductor is weakened so that the toner image can be easily peeled off, thereby improving the transfer efficiency in the toner image transfer process. Can be made.

[Brief description of drawings]

Figure 1: Chromium complex salt dye (2: 1 type) as charge control agent
3 is an absorbance curve at a wavelength of 400 to 700 nm of an extract obtained by extracting the toner containing the toner with methanol.

FIG. 2 is a wavelength of a methanol extract of a toner using a salicylic acid metal complex as a charge control agent at a wavelength of 280 to 350 nm.
It is an absorbance curve in.

FIG. 3 is a diagram showing the carrier used in the measurement of FIG. 1 as a two-component magnetic developer, and a carrier in which poor charging due to a spent occurs is similarly extracted with methanol, and the absorbance of the extract at a wavelength of 400 to 700 nm. It is the graph which measured the curve.

FIG. 4 is a graph plotting a relationship between a mixing time and a spent amount when a mixture of a toner containing a charge control agent and a magnetic carrier and a mixture of a toner containing no charge control agent and a magnetic carrier are mixed. is there.

FIG. 5 is a graph plotting the relationship between the mixing time and the charge amount when a mixture of a toner containing a charge control agent and a magnetic carrier and a mixture of a toner containing no charge control agent and a magnetic carrier are mixed. Is.

FIG. 6 is a graph showing the relationship between the amount of spent spent carrier and the charge control agent in spent toner.

FIG. 7 is a graph showing the relationship between the mixing time and the amount of spent when the individual components in the toner are mixed with the magnetic carrier.

FIG. 8 is an explanatory diagram illustrating the occurrence of charging failure due to spent generation in a conventional two-component magnetic developer.

FIG. 9 is a wavelength range of 280 to 350 nm and a wavelength range of 400 to 70 of an extract obtained by extracting the toner of the present invention with methanol.
It is an absorbance curve at 0 nm.

Front page continuation (72) Inventor Kazuya Nagao 1-22 Tamatsukuri, Chuo-ku, Osaka Mita Engineering Co., Ltd.

Claims (2)

[Claims] 1. A negatively charging toner for a two-component magnetic developer, wherein the fixing resin medium is a copolymer resin or a resin composition having an anionic polar group, and 0.1 to 100 parts by weight of the resin medium is used. Wavelengths 400 to 7 of the extract liquid containing 5 parts by weight of magnetic powder and obtained by extracting the toner with methanol.
A toner for a two-component magnetic developer excellent in spent resistance, characterized in that the absorption peaks at 00 nm and 280 to 350 nm are substantially zero. 2. A negatively chargeable toner for a two-component magnetic developer, wherein the fixing resin medium is a copolymer resin or resin composition having an anionic polar group, and 0.1 to 100 parts by weight of the resin medium. Wavelengths 400 to 7 of the extract liquid containing 5 parts by weight of magnetic powder and obtained by extracting the toner with methanol.
Absorption peaks at 00 nm and 280 to 350 nm are substantially zero, and the particle size is 5 to 15 μm on a volume basis.
And a fine powder fluidity improving agent containing spacer particles having a particle diameter of 0.05 to 1.0 μm on a volume basis are adhered to the surface of the toner particles. Toner for component type magnetic developer.